Detection of Butyrylcholinesterase in Vitro

A new assay has been developed for detection of butyrylcholinesterase (EC 3.1.1.8) activity based upon the change in absorbance of phenol red, caused by the r e l ease of bu ty r i c acid from the substrate. Using c o m m e r c i a l l y avai lable enzyme prepared from horse serum, linear, dose-related decreases in absorbance were obtained, generally with correlation values of 0.965 or greater. The assay was modified and used to detect enzyme a c t i v i t y in the supe rna tan t s from primary cultures of mouse hepatocytes. The enzyme-mediated r e s p o n s e was i n h i b i t e d by N N ' d i i s o p r o p y l phosphorod iamid ic anhydride, a specific inhibitor of butyrylcholinesterase.